Interpretation
Interestingly, in the OBS2 study, fibrinogen was administered after
immediate estimation of fibrinogen levels using the Rotem
viscoelastomeric point-of-care test 17. A nearly
two-fold decrease in total allogenic blood product transfusion rate was
observed in women with plasma fibrinogen concentrations estimated below
2.0 g/L and supplemented with fibrinogen. The difference was not
significant however due to a lack of power. Our study and its negative
results further contributes to the attractiveness of rapid plasma
fibrinogen assays for initiating and guiding treatment when necessary,i.e. only in the most severe cases associated with coagulopathy
and low fibrinogen levels 15.
Thus, three major randomized and well conducted controlled studies,
FIB-PPH, OBS2 and FIDEL, all found that early fibrinogen replacement is
not beneficial in the course of severe PPH management when a second line
uterotonic agent is needed after prostaglandins and when plasma
fibrinogen level is not known. Nonetheless, several other and older
observational studies or reports from the UK, Japan, or Turkey still
maintain that fibrinogen supplementation is effective and beneficial14,28-32. This is not surprising, as most patients in
those studies presented very severe and advanced PPH, and much greater
blood loss and much lower plasma fibrinogen concentrations (usually
< 1 g/L) than those reported in the randomized studies.
Although the patients received numerous transfusions (including fresh
frozen plasma, FFP) and were not compared with adequate control groups,
the studies documented safety and established the usefulness of massive
doses of fibrinogen (up to 8 g) to avoid FFP transfusion, fluid
overload, and for rapid correction of very low fibrinogen levels.
Although the randomized controlled trial is the gold standard
methodology for demonstrating the efficacy of a therapeutic strategy, it
is not always adapted to field constraints, especially in
life-threatening emergencies. In light of this, observational or
uncontrolled studies provide potentially biased, but better targeted
data, which are truly informative and complementary to those of
randomized controlled trials.
Altogether, these studies back the use of a targeted strategy to adjust
the supplementation to the fibrinogen level estimation. Because
fibrinogen decrease may be drastic in PPH 33,34, and
because a prompt therapeutic answer is expected, newly available
“plug-and-play” viscoelastometry bedside devices allowing a quick and
convenient assay in the emergency room are very useful tools. This
approach can help clinicians identify coagulopathies in “real-time”
and when emergency fibrinogen supplementation is required, especially in
severe cases of PPH, or in specific situations such as placental
abruption or amniotic fluid embolism 33,34.